CHAPTER-4 ELEMENTARY STUDENTS’ CONCEPTIONS ABOUT FOOD AND NUTRITION 4.1 Introduction 4.2 Scientific Evolution of the Concept: Food and Nutrition 4.3 Pedagogical Perspective of the concept: Food and Nutrition 4.4 Development of the Concept Maps: Food and Nutrition 4.4.1 The Intended Concept Map: Indian Source 4.4.2 The Intended Concept Map: International Source 4.4.3 The Derived Concept Map: Food and Nutrition 4.5 Students’ Conceptions of Food and Nutrition: Primary Source 4.5.1 General Analysis of Students’ Conceptions about Food and Nutrition 4.5.2 Comprehensive Analysis of Students’ Conceptions about Food and Nutrition 4.5.2.1 Students’ Conceptions about Food and Nutrients 4.5.2.2 Students’ Conceptions about Digestion 4.5.3 Discussion 4.6 Conclusion
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CHAPTER-4
ELEMENTARY STUDENTS’ CONCEPTIONS ABOUT FOOD AND NUTRITION
4.1 Introduction
4.2 Scientific Evolution of the Concept: Food and Nutrition
4.3 Pedagogical Perspective of the concept: Food and Nutrition
4.4 Development of the Concept Maps: Food and Nutrition
4.4.1 The Intended Concept Map: Indian Source
4.4.2 The Intended Concept Map: International Source
4.4.3 The Derived Concept Map: Food and Nutrition
4.5 Students’ Conceptions of Food and Nutrition: Primary Source
4.5.1 General Analysis of Students’ Conceptions about Food and Nutrition
4.5.2 Comprehensive Analysis of Students’ Conceptions about Food and Nutrition
4.5.2.1 Students’ Conceptions about Food and Nutrients
4.5.2.2 Students’ Conceptions about Digestion
4.5.3 Discussion
4.6 Conclusion
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CHAPTER-4
ELEMENTARY STUDENTS’ CONCEPTIONS ABOUT FOOD AND NUTRITION
4.1. Introduction
Food is the source of energy and matter for all organisms and is one of the
links between them. The way we use the term food in everyday language
depends on the context. Text books used in schools describe food in a variety
of ways. There is a lack of an agreed definition of food by scientists (Barker,
1985, as quoted by Francis and Hill, 1993). Food as a concept is fraught with
the semantic problem of the word food having different meanings in everyday
and scientific contexts (Driver et. al, 1994). The school science definition of
food, as organic compounds, which organisms use as a source of energy for
metabolic processes, is not consistently used by science educators. Some text
book authors consider water as food since it has minerals, some do not since
water is not organic. Nutrition is the process by which living organisms obtain
food and use it for growth, metabolism and repair. The stages of nutrition
include ingestion, digestion, absorption, assimilation and excretion. Food
provides matter and energy to the plants and animals and is the link between
inanimate things like gases, minerals, water etc and the living world. Food and
nutrition is an important component of Biology linked with Human Physiology,
Ecology, Nutrition and Dietics and other similar subjects.
The concept of food and nutrition is introduced from early elementary classes
and even to pre-primary children since it is integrally linked to our well-being
and health. While the sub concepts of variety of food, healthy food and junk
food, hygiene, healthy food habits are part of primary classes; components of
food, role of various nutrients in human body, plant nutrition, digestion and
nutrition in animals (humans), management of food resources etc are part of
upper elementary curriculum.
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The following section traces the evolution of the concept of food and nutrition
historically from the time of Hippocrates.
4.2. Scientific Evolution of the Concept: Food and Nutrition
The concept of Food and Nutrition has been evolving since 400 BCE when
Hippocrates said that food has a positive effect on our health and well being.
But the major ideas evolved since mid of eighteenth century till the present.
Around 1770, Antoine Lavoisier, the “Father of Nutrition and Chemistry”
discovered the details of metabolism demonstrating that the oxidation of food is
the source of body heat. In 1790, George Fordyce recognized calcium as
necessary for fowl survival. In the early 19th century, the elements- carbon,
nitrogen, hydrogen and oxygen were recognized as the primary components of
food, and methods to measure their proportions were developed.
In 1816, Francois Magendie discovered that dogs fed only with carbohydrates
and fat lost their body protein and died in a few weeks, but dogs also fed with
protein survived, identifying protein as an essential dietary component. In 1747,
Dr. James Lind a physician with British Navy discovered that the sailors who
were given limes were saved from scurvy while others suffered. Vitamin-C was
discovered much later in 1930’s as a vital nutrient. It was discovered in early
1800s that food is composed mainly of four elements: carbon, hydrogen,
oxygen and nitrogen. J. Leibig of Germany was the first to point out chemical
makeup of carbohydrates, fats and proteins in 1840. One by one all vitamins
were discovered in early 20th century. Since 1950s to the present, the role of
essential nutrients as part of bodily processes has been brought to light.
Fibre became a household word back in 1970s when Dr. Denis Burkitt, a man
nicknamed the Fibre Man, and his colleagues made “the fibre hypothesis” that
states that fibre can prevent certain diseases. Through their work in Africa, they
discovered that diseases that were common in the Western cultures were not
common there. These included heart attacks and high blood pressure
(cardiovascular diseases) obesity and diabetes (metabolic disorders), intestinal
problems (constipation, gallstones, appendicitis and colon cancer), varicose
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veins and blood clots (deep vein thrombosis). The primary dietary difference
was the high intake of fibre and low intake of refined carbohydrates in the
African population. Burkitt also noted the emergence of these diseases in the
United States and England after 1890 following the introduction of a new milling
technique that removed fibre from whole grain flour to produce white flour. More
became known about the role of vitamins and minerals as components of
enzymes and hormones that work within the body. Synthetic enzymes and
vitamins were synthesized.
The idea about human nutrition kept evolving since the ancient anatomists.
Ancient and medieval anatomists had fairly accurate gross physiological
knowledge of the structure of stomach, intestines and colon. They recognized
the importance of digestion as a key aspect of maintaining the humoral balance
of the body. Initially medical practitioners viewed the stomach as an active,
almost thinking agent in the body. Galen additionally described it as a store
house of nutrition that sorted the ‘wheat from the chaff’ meaning that stomach
has a filtering effect also. In the Galenic tradition, it was the site of first
digestion, since the body digested nutrients in multiple ways. Every aspect of its
shape and texture – even its location – facilitated this process. Master Nicolaus
in the twelfth century poetically wrote: “The stomach has the liver below it like a
fire underneath a cauldron; and thus the stomach is like a kettle of food, the
gall-bladder its cook, and the liver is the fire.” Similarly, the names of parts of
the digestive system recalled their specific functions. Many thought that the
colon was a colander that strained the faeces.
Increased dissection led to more detailed descriptions of the organs involved in
digestion and illustrations were drawn of the organs and their internal
structures. Leonardo da Vinci believed that the digestive system aided the
respiratory system in its function. In the mid-seventeenth century, a Flemish
physician Helmont offered the first chemical account of digestion and placed
emphasis on the stomach as a chemical laboratory (known as alchemist theory
of medicine).
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By 1825, Dr. Beaumont began to experiment on digestion using an open
wound in the stomach of St. Martin, a wounded soldier. Dr. Beaumont worked
on the samples of stomach to digest bits of food in cups. This established that
digestion was primarily a chemical process and not a mechanical one. In 1835,
German physiologist Theodor Schwann discovered the non-acidic component
of gastric juice which he named pepsin (to digest’ in Greek) which was later
shown to be an enzyme. In 1897, another German scientist, Eduard Buchner,
discovered by accident that fermentation actually does not require the presence
of living yeast cells. Buchner made an extract of yeast cells by grinding them
and filtering off the remaining cell debris. Then he added a preservative-sugar
to the resulting cell-free solution to preserve it for future study. He observed that
fermentation, the formation of alcohol from sugar, occurred. Buchner then
realized that living cells were not required for carrying out metabolic processes
such as fermentation. Instead, there must be some small entities capable of
converting sugar to alcohol. These entities were enzymes. Buchner’s accidental
discovery won him the 1907 Nobel Prize in Chemistry.
Thus, scientific methods of inquiry, imagination of brilliant minds, in addition to
discovery of technological instruments have helped humanity develop an
understanding about food and nutrition (Refer to figure 4.1).
From the timeline of food and nutrition, it is understood that evolution of food
and of nutrition occurred independently. Evolution in food and digestion
stemmed from speculation: speculation about effects of food with health,
speculation about role of different organs or glands in the body. Interpretation of
observations of experimentations leads to generalisations such as those of Dr.
Beaumont. From the study of the evolution of food and nutrition, the
implications for school science is that alternate conceptions of students are
important starting points for subsequent scientific understandings. Students
may comprehend generalisations about food and nutrition from explanation of
experiments and subsequent theory-building. Learners would probably
understand and describe concepts related to food first, and then understand
nutrient of food. Explaining or emphasising the need of including a component
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or nutrient into diet may not useful for learners till they comprehend the
biochemical nature of its transformation inside the body. Hence the attention of
students also needs to be drawn to conceptual explanation behind chemical
transformation of food, absorption and assimilation.
Fig. 4.1: Time Line – Food and Nutrition
4.3. Pedagogical Perspective of the Concept: Food and Nutrition
Food and digestion is a topic fundamental to most science curriculum and a
core concept of living things. Digestion relates to other major life processes
Food and Nutrition
400-BC-Hippocrates-food has
positive effect on our health
1567-Helmont-Given an account
about digestion
1651-Harvey-Living things
Originate from eggs.
1747-James Lind-
Discovered Vitamin C
1770- Antoine Lavoisier-
Became father of nutrition
and Chemistry
1790- George Fordyce-
Recognized calcium
Francois-1816- Invented
the importance of dietary
protein
1840-J.Leibig- Chemical
makeup of carbohydrates
1897- Eduard Buchner-
invented enzyme
1905- William Fletcher- Identified the
role of essential nutrients Dr. Denis Burkitt- Invented
fibers and its use full ness
for good health
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such as respiration, circulation, excretion and growth. Therefore teaching of this
concept requires particular attention in science education. Food, eating and
digestion are inter-related concepts and curriculum places emphasis on the
development of knowledge and attitudes in school children that are conducive
to healthy nutrition and living.
The historical evolution of the concept of food and nutrition has shown that a
complete understanding of nutrition is an ongoing endeavour on the part of the
scientific community comprising of nutrition specialists, molecular biologists,
medical practitioners, chemists among others. Sophisticated concepts of food
and human nutrition have emerged as part of interdisciplinary research. The
discovery of various aspects of food and nutrition over the human history has
helped humans have a cogent area of knowledge about human nutrition.
Though new discoveries are being made about the role of enzymes, or proteins
or other bio-molecules, they are at the ultra-cellular and at times sub-atomic
level and pertain to medical sciences and not the science teaching till
secondary level per se. Understanding the pedagogical aspect of the concept
of food and nutrition would help the researcher to build a more complete
comprehension of the difficulties if any in the understanding of the concept by
elementary students and to finalise the conceptual statements based on which
questions would be framed. Much of children’s ideas about food and digestion
have been compiled in the research summary developed by Leeds National
Curriculum Science Support Project, 1992 with the aim to help teachers.
Pedagogical perspective has been collated from the above summary and other
research conducted by nutritionists, and other researchers from the perspective
of science education or child development.
Children and most adults consider food as that which is fit for human
consumption; i.e, food is something which is eaten. They usually extend it to
mean anything useful taken into an organism’s body, including water, minerals.
From an early age, children seem to know that eating has many consequences:
growth, health, strength and energy. From the age of eight, most children
differentiate different kinds of diets as making people fat or strong. Contento
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(1983) found that children in concrete operational stage can classify concrete
items such as foods into groups and understand that food is changed in some
way in the stomach, but they do not know how the effect was brought about.
In the everyday context, children and most adults think food as something we
eat. Food is thought of as solid and not drinks/beverages. Learners identify
food as material to provide growth, health and activity. They do not recognise
that food is source of material to become part of their bodies in growth or that
food is source of energy. Children( 5 to 11 years) do not refer to a transfer of
matter from the environment to the organism, though some children do explain
the growth of animals by stating that the organism has to ‘stretch’ to make room
for the food eaten( Russell and Watt ,1989). Smith and Anderson (1986)
suggested that many 11 to 12 year olds conceptualise food as something that
can be created and destroyed, and converted directly into energy. According to
Barker (1986), older secondary school students’ use of edibility and palatability
as criteria of food gets replaced by the energy criterion. The benefits of eating
food to organisms are seen as an example of cause-effect reasoning rather
than as a transformation of matter from one form to another.
From an early age, children, know that what we eat consists of proteins, fats,
vitamins etc, but they do not understand function of these substances and do
not recognise them as groups of materials. They do not distinguish the food we
eat from the components, for example, they have the notion that bread is
starch, pulses are protein etc. They may not understand the cellular or
molecular nature of food (Simpson, 1984).
Young children have various notions about their body parts like stomach and
digestion of food .They imagine their body to be hollow bag, which is all
‘stomach’ containing food, blood and wastes (Gellert, 1962). The youngest
children relate the stomach to breathing, blood or strength and energy. From
about seven they begin to know that the stomach helps to break or digest food,
and later that food is transferred elsewhere after being in the stomach and by
age 9, most children listed several organs including the stomach. Older children
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realise that there is a food bag inside the body, but use ‘stomach’ to apply to
both stomach and abdomen. Gellert, 1962 found that by 11, most children had
a fairly correct outline of anatomy and the overall function of systems. She
attributed the initial ideas to sensations of heartbeat and swallowing, and later
ideas to TV and hospital experience. Many think that digestive system has two
outlets, one for feaces and one for urine.
A very common concept amongst children is that digestion is the process which
releases usable energy from food. This arises from linking the two acceptable
ideas ‘energy’ is obtained from food’ and ‘digestion is the breakdown of food’ to
construct an unorthodox idea.
Simpson (1984) found that at thirteen, children’s ideas of the sequences of
digestion are very confused, both in terms of the anatomical route and the
processes. Routes may include the trachea, heart, kidneys in some children’s
minds. The sequence of processes may start with breaking into soluble
particles, releasing energy, followed by swallowing. These ideas are not naïve
intuitive notions but construction derived from an overload of information. Pupils
have been taught a lot of unfamiliar words or familiar words in a new context.
Leeds National Curriculum Science Support Project (1992) researched and
reviewed existing research into children’s ideas about nutrition and concluded
that the challenge for elementary students is to accept that digestion is not an
end in itself but an intermediate stage between eating and building new body
substances or releasing energy. The challenge can be tackled at two levels: (1)
working and refining everyday words connected with digestion into scientific
meanings. (2) for a deeper level understanding, developing the concepts of
conservation of matter and matter being rearranged. Further, understanding of
digestion depends on previously established concepts of solids, liquids and
solubility.
Assimilation of food is central to understanding much of biology (Driver, 1994).
Conceptual understanding in most aspects of nutrition would be achieved if
learners understand that what we eat actually becomes skin, bone, blood etc
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(and what plants make, becomes leaves, wood etc.). Understanding bio-mass
may be a useful step for learners to realise that bio-mass consists of products
of chemical interactions and may act as reactants in further chemical
interactions. Once learners have developed particle ideas, they may be able to
integrate assimilation with rearrangement of atoms.
Table 4.1: Investigators Studying Conceptions of Elementary Students about various Food and Nutrition Concepts
Sub-concepts of Food and Nutrition
Investigators
Below 9
yrs
4th
(9 yrs)
5th
(10 yrs)
6th
(11 yrs)
7th (12 yrs)
8th
(13 yrs)
Nutrients in Food Arnold and Simpson (1980)
Food-Concept Barker (1985) � � � � �
Consequences of food Carey S. (1985) � � �
Food – source of energy Leach, Driver et al. (1992)
� � � � � �
Food-source of energy Francis and Hill (1993)
�
Classification, importance of nutrients
Sheila Turner (1997) � � �
Nutrients and health Dixey, Sahota et al. (2001)
� � �
Food groups, nutrients & health
Hart,Bishop and Truby (2002)
� � � �
Digestive organs and their role
Gellert (1962) � � � � � �
Enzymes egestion Simpson (1984) �
Respiration & digestion Nunez and Banet (1997)
� � �
Structure & function of D.S Texeira (2000) � � �
Digestive system Reiss and Tunnicliffe (2001)
� � � � � �
Digestion process,circulation
assimilation Carvalho (2004) � � �
Digestion process Cakici Y. (2005) � �
Digestive system-figure Mathai and Ramadas (2009)
� � �
Digestive system & respiratory system-figure
Susana Gracia-Barros et al. (2011)
�
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Researchers have researched into students’ conceptions of food and nutrition
using techniques and tools according to various perspectives starting from pre-
primary children to adults (Table 4.1). From all the available research in the
area of elementary students’ understanding of food and nutrition concepts, one
can infer that research on food is a strand separate from the nutrition strand.
Mostly researchers have investigated in either of the strand. Researchers have
investigated on the sub-concepts of meaning of food as perceived by learners,
classification into food types, importance of nutrients in our body and impact of
food on health. Within the digestion and nutrition strand, the sub-concepts
investigated are about the structure of digestive system, understanding about
role of mouth, stomach intestines etc., and concepts about assimilation,
absorption and the relation between concepts of energy, matter and digestion.
The concepts investigated with youngest children are often, meaning and
classification of food (Contento, 1983), structure of digestive system (Gellert,
1962) and children’s perceptions about nutrition and growth (Leach et al., 1992)
and conceptual understanding about relation between digestion and other life
processes are investigated of older learners (Table 4.1) .
Learners are able to relate to concepts of food easily than those of nutrients
which needs understanding about particulate nature of matter. The challenge
for elementary students is to accept that digestion is not an end in itself but an
intermediate stage between eating and building new body substances or
releasing energy. This would be progression of learners towards sophisticated/
integrated food and nutrition concepts which seems difficult at the elementary
level without pedagogical efforts directed towards that end.
Having known the conceptual resource of learners from the pedagogical
perspective about food and nutrition prepares the researcher to develop
questions to generate primary data.
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4.4. Development of the Concept Maps: Food and Nutrition
Concept maps were developed to fulfil the following objectives:
a. To understand what the intended curriculum includes in the area of food
and nutrition in Indian context
b. To identify what constitutes ‘standard’/expected knowledge in the area from
available curricular resources and
c. To derive a concept map from the maps at a) and b) above and to form a
basis for developing questionnaire
Concept maps can be defined as visual representations that are added to
instructional material to communicate the logical structure of the instructional
material. The concept map serves as a device to illustrate the hierarchical
conceptual and propositional nature of knowledge. The concepts are arranged
in a hierarchy with a super ordinate concept at the top. The concepts are linked
by lines labelled with connecting words that form the proposition uniting the
concepts. Concept mapping requires the mapper to prioritise and make
judicious use of selected concepts when mapping (Novak and Gowin 1984). It
involves identification of concepts in study materials and their organisation from
the most to least general and more specific concepts.
Concept maps are flexible tools that can be used in a variety of educational
settings (Stewart, Van-Kirk and Rowell, 1979).They have been used as a tool
for assessing meaningful learning (Novak, 1979) as well as in curriculum
planning, instruction and evaluation( Stewart et al,1979).Concept maps are
useful in science curriculum planning for separating significant from trivial
content (Starr and Krajcik, 1990) and focussing the attention of curriculum
designers on teaching concepts and distinguishing intended curriculum from
instructional techniques (Stewart et al, 1979). Science educators extract, select
and prioritize concepts from information-dense materials (Jonassen, Biessner
and Yacci, 1993). Science education reforms have developed concept maps to
decide which concepts are the most important to learn and use what are
important concepts that contribute the big picture or pervasive principles at the
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core of scientific disciplines. Science curriculum reforms in USA and Australia
are such cases and are being presented in the following paragraphs.
AAAS Project 2061 and the National Science Teachers Association (USA)
published two volumes of Atlas of Science Literacy including nearly 100 maps
which chart all the learning goals specified as ‘Benchmarks’ essential for every
student to learn. The maps given in the Atlas of Scientific Literacy illustrates the
relationships between individual learning goals and shows the growth of
understanding of ideas. Connecting arrows indicate the connections between
ideas which are based on the logic of the subject matter (or on cognitive
research about how students learn). The maps are available at